What are the permited top speeds of the NYC subway and London's tube.?

Question

The NYC subway ran up to 50 mph ( 80km/h) for many years, but this may no longer be so.

I assume the trains themselves are capably of say 80-90 mph

( 130- 145 Ks).

Answer 1

No public subway system exceeds 60 MPH anywhere in the world due to the inherent design.

The DC Metro's fastest speed is 59 MPH even though the speedometers on the modern trains can go to 70.  The subways are operated automatically and a speeding driver could jeopardize the schedule unless other drivers go as fast as he does.